Kirchmaier, who is also California's oldest licensed driver and the University of Chicago's oldest living former student, joined Facebook last month. Direct Relief, a medical aid charity where she's volunteered for 40 years, set up the account in honor of her 105th birthday.

"I've been contacted by such wonderful people and received such nice messages and pictures from people all over the world," Kirchmaier said. "I'm so humbled by all the interest in me."

Born into the age of telegraphs and rotary dial telephones, Kirchmaier said she embraces social media because it allows her to check in daily with friends and family. She said she's especially interested to see how many people log on to light a virtual candle in her honor, a symbol they've liked the fan page of Direct Relief.

"I'm hoping to get 105,000 likes for the page," she said.

While Kirchmaier is the oldest person on Facebook, she is hardly the only senior to embrace social media. The social site's demographics have grown steadily grayer over the past few years.

Retirees age 65 and older are the fastest-growing group of social networkers on sites such as Facebook, LinkedIn and MySpace, according to a 2012 survey by the Pew Research Center's Internet and American Life Project. The report found that 40 percent of Internet users older than 65 use Facebook, up 150 percent since 2009.

Golden-agers are also signing onto Twitter in record numbers. In 2009, only 5 percent of Internet users in the 50 to 64 age bracket had used Twitter, or some other status-update service. It's now up to 11 percent.

Kirchmaier said she didn't yet have a Twitter account but finds the idea of communicating in 140 characters or less intriguing. "I just may give it a try," she said.

Seniors log on to social media to stay in touch, reconnect with people from their past and seek support for chronic health conditions, the Pew report found. A University of Alabama at Birmingham study suggested that Internet use was associated with a 30 percent decrease in depressive symptoms among older adults who used it regularly.

"One of the greatest benefits of social media for older people is learning they're not alone," said Kristi Grigsby, director of communications for the website ageingcare.com. "It helps them focus their attention on something other than being old."

But Joe Buckheit, Aging Care's president, warned about the potential danger for seniors who cruise social sites: They're frequently targeted by "granny scammers," con artists who've caught onto the fact that older folks are flocking to social media to share details about their personal lives.

A common "granny scam" is "the relative in distress." A thief grabs personal information from an elderly person's Facebook page, then phones the person masquerading as a loved one who's gotten into an accident and is in dire need of cash. The Federal Trade Commission reported that 60,000 complaints about this type of fraud were filed last year.

To protect elders, Buckheit advised making sure they are aware of the scam. Instruct them to ask detailed personal questions if they get a call from a panicked relative and to hang up and call the relative back on a known number. They need to verify the information with another relative. If the caller says to keep it a secret, that's a red flag.

If they've already fallen prey to a scam, Buckheit said to stop payment on any checks or wire transfers immediately and contact both the police and the three credit bureaus to let them know there's been a possible crime committed.